Description of the Related Art
Known as a mold for curing an uncured tire (hereinafter referred to simply as “tire”) is a mold combining a base mold serving as a base member and a pattern mold formed thinner than the base mold and serving as a surface member. Disclosed in Patent Document 1 is a mold having the fitting surfaces of the base mold and the pattern mold of substantially the same peripheral length thereof.
A plurality of the above-mentioned molds are so arranged as to circumferentially surround the crown region of a tire within a curing apparatus. And an annularly enclosed space surrounding the crown region of the tire is formed with the circumferential end faces of the base molds and the circumferential end faces of the pattern molds of the circumferentially adjacent molds joined closely to each other. Also, the pattern mold has recesses and projections formed thereon corresponding to the tread pattern and design to be formed on the crown region of the tire to be cured. And, using such a mold, a tire with different tread pattern can be cured by simply replacing the pattern mold fitted to the base mold with another pattern mold having different recesses and projections thereon.
However, the pattern mold has not only the recesses and projections but also tiny air vent holes for discharging air that is trapped between the periphery of the pattern mold and the tire surface during the curing process. And the air vent holes are located with consideration given to the shapes and positions of the recesses and projections. Also, the air vent holes are communicated with the discharge passages provided within the base mold. And the air led out of the air vent holes is discharged out of the mold after passing through the discharge holes and passages formed inside the base mold.
That is, with the above-described mold, the same base mold cannot be used when there is any change in the positions of the air vent holes as a result of pattern mold replacement. It is therefore necessary to prepare in advance another base mold having discharge holes corresponding in positions to the air vent holes in the new pattern mold. This leads to longer period of mold manufacture and higher cost.